Rotary regenerative heat exchangers

ABSTRACT

Regenerator end sealing plates which move axially with the thermal expansion of the rotor are prevented from tilting by stabilizing means.

United States Patent [191 Pettersson et a1.

ROTARY REGENERATIVE HEAT EXCHANGERS Inventors: Birger Pettersson, Alta; Kurt Karlsson, Tyreso, both of Sweden Assignee: Svenska Rotor Maskiner Alrtiebolag,

Nacka, Sweden Filed: Sept. 7, 1971 Appl. No.: 178,248

Foreign Application Priority Data Sept. 8, 1970 Great Britain 42933/70 U.S. CI. 165/9 Int. Cl. F28d 19/04 Field of Search...; 165/9, 8

[ 1 Jan. 15, 1974 [56] References Cited UNITED STATES PATENTS 2,873,952 2/1959 Mudersbach et al. 165/9 3,010,703 11/1961 Bellows et al 165/9 3,250,316 5/1966 'Nyberg 165/9 FOREIGN PATENTS OR APPLICATIONS 200,703 11/1965 U.S.S.R 165/9 Primary Examiner-Albert W. Davis, Jr. Attorney-Robert D. Flynn et al.

[57]' ABSTRACT Regenerator end sealing plates which move axially with the thermal expansion of the rotor are prevented from tilting by stabilizing means.

11 Claims, 8 Drawing Figures Pmmimms 1914 3785431 SHEE'I 1 BF 5 Fig.7

20 GAS PATENTEI] JAN 15 I974 SHEEI '3 OF 5 PATENTEBJAM 15 1974 SHEET 5 BF 5 Fig. 7

ROTARY REGENERATIVE HEAT EXIIIHANGERS This invention relates to rotary regenerative heat ex changers of the type which comprises a housing, a rotor mounted in said housing, said rotor including a central rotor post and a cylindrical shell interconnected by radial partitions subdividing the rotor into a plurality of open-ended sectorial compartments for a heat exchanging mass, said housing being provided with inlet and outlet ducts for a heating fluid and a fluid to be heated and said rotor being joumalled at one end in a thrust bearing means and at the other end in a radial bearing means permitting axial movements of said other end due to thermal expansion. and contraction of said rotor in axial direction, and axially movable plates between the rotor end surfaces and the end walls of the housing forming sealing means to prevent intermingling of the flows of heat exchanging fluids in the space be? tween said surfaces and said end walls, said sealing plates including at each end of the rotor a central plate element and two radially extending outer plate elements hingedly connected to two opposite edges of the central plate element, at least one member of said radial bearing means being mounted to move axially together with said other rotor end, and the central plate element of the adjacent sealing plate being held by said bearing member. I

Heatexchangers of this type are often used asair preheaters in boiler plants in which the combustion gases used as heating medium may have a temperature of 350C or more. In cold condition the rotor has the form of .a flat cylindrical disc but when heated by the combustion gases it does not only undergo thermal expansion but in addition it becomes dished.

In an air preheater the pressure of the air to be heated is higher than the pressure of the combustion gases and therefore the air has a tendency to leak over to the gas side of the preheater. Since such leakage involves losses it must be kept as small as possible. Due to the contents of ash and soot in the combustion gases it is necessary to provide a small clearance between relatively movable sealing surfaces in order to prevent wear due to the grinding action of the ash and soot particles. However, this clearance must be kept as small as possible and due regard must be paid to the thermal deformation of the rotor.

In air preheaters having movable sealing plates of the type described the outer end of each outer sealing plate element at one rotor end is usually connected to the outer end of the outer sealing plate element at the other rotor end axially aligned therewith and the swinging system thus formed is counter-balanced by a counterweight whereby the sealing plates are floating. Such arrangements are shown for instance in British Pat. specification No. 1,] 18,710. In this way the dishing of the rotor is at least partly compensated for by the swinging system which adapts itself to the form of rotor.

The influence of the thermal axial expansion and contraction of the rotor upon the width of the clearance is eliminated by the connection between the central sealing plate element adjacent to the radial bearing means and the axially movable member of the bearing.

The heat exchanging mass offers a resistance to the fluid flows resulting in a pressure drop so that the fluid pressure upstream of the preheater is always higher than the pressure downstream thereof. Therefore, when a rotor compartment during its passage from the air side to the gas side of the preheater has reached a position between the sealing plates in which it is still in communication with the air side thefloating plate system will be pressed towards the cold end of the preheater by the pressure difference. However, as the compartment is shut off from the air side by the trailing partition and immediately afterwards is put into communication with the gas side the system is pressed in opposite direction. In this manner the sealing plates will oscillate continuously during operation.

Corresponding oscillations of opposite phase are produced by compartments passing from the gas side to the air side.

The oscillations just described have several unfavourable consequences such as increased leakage, increased wear of the hinges and undesired pulsating bending or tilting forces acting upon the central sealing plate elements. These forces cause particular difficulties at the axially movable central plate element.

SUMMARY OF THE INVENTION The invention has for its object to provide means whereby to obviate the above-mentioned drawbacks and to attain this object the heat exchanger according to the invention is characterized by stabilizing means included in the connection between the axially movable member of the radial bearing and the adjacent central plate element and adapted to prevent tilting of the central plate element during operation of the heat exchanger.

This and other features of the invention will be apparent from the following description of an embodiment of the invention shown in the accompanying drawings in which FIG. 1 is an axial partial sectional view of a rotary regenerative air preheater embodying the invention and diagrammatically illustrates the general design of the preheater,

FIG. 2 is a plan view on a larger scale of a portion of the preheater as seen from line IIII in FIG. 1,

FIG. 3 is a cross-section along line Ill-III in FIG. 2,

FIG. 4 is a cross-section along line IV-IV in FIG. 2,

FIG. 5 is a cross-section along line V-V in FIG. 2,

FIG. 6 is a view of a portion of the preheater as seen from below in FIG. 1,

FIG. 7 is a cross-section along line VII-VII in FIG. 6 and FIG. 8 is a perspective view illustrating the complete stabilizing system.

The preheater shown in FIG. I is of the well-known general type having a rotatable cylindrical regenerator body or matrix forming a rotor 10. The rotor consists of a trunnioned central rotor post 12 and a cylindrical shell 14 interconnected by radial partitions (not shown) subdividing the rotor into a plurality of openended sectorial compartments each containing a heat exchanging mass usually in the form of packages 16 of corrugated plate elements.

The rotor I0 is mounted in a housing comprising a cylindrical peripheral wall 18. The end walls of the housing are defined mainly by the inlet and outlet ducts for the heat exchanging fluids. Thus, in FIG. 1 duct 20 may be assumed to be the inlet duct for the hotflue gases and duct 22 the outlet duct for the cooled gases. Accordingly there is an inlet duct 24 and an outlet duct 26 for the air as fragmentarily indicated at the left hand side of the figure.

The ducts 20 and 26 at the upper end of the housing are separated by a beam 28 of U-shaped cross-section which extends diametrically across the upper end surface of the rotor and the flanges of which form parts of the duct walls. A similar beam 30 is provided at the lower end of the housing.

The axially aligned ends of the beams 28, 30 are rigidly interconnected by vertical pillars (not shown) which together with the beams form a rigid rectangular frame supporting the housing structure and resting on a firm and stable foundation (not shown).

The rotor 10 is carried by a combined thrust and radial bearing 32 receiving the lower trunnion 12A of the rotor post 12. This bearing 32 rests on a platform 34 at the top of a column structure 36. Thus, the frame formed by the beams 28, 30 and the pillars is relieved of the load from the rotor. The upper trunnion 12B of the rotor post 12 is guided by a radial bearing 38 movably connected to the upper beam 28 in a manner to be described below.

In order to prevent intermingling of the gas and air flows there are provided sealing plates 40 between the beams 28, 30 and the end surfaces of the rotor 10. In addition, the annular space between the rotor shell 14 and the peripheral housing wall 18 is sealed off by resilient sealing strips 42 secured to the wall 18 and slidingly cooperating with the outside of peripheral rings 44 at the ends of the rotor 10.

In FIG. I the radial bearing 38 and its connections with the beam 28 and with the upper sealing plate 40 are shown schematically. These elements will now be described more in detail with reference to FIGS. 2 to According to FIGS. 2 to 4 the radial bearing 38 comprises a housing 46 in which are mounted the outer races of two axially spaced ball bearings 48 and 50. The inner races of these ball bearings are separated by a spacer sleeve 52 and the inner race of the lower ball bearing rests on a spacer element 54 which in turn is carried by a shoulder 56 on the upper trunnion 12B of the rotor post 12. In this manner the whole bearing assembly 38 is carried by the end portion of the trunnion 128.

When the rotor post 12 expands and contracts thermally the bearing 38 moves vertically. This movement is guided by a fork structure 60 carried by a shaft 62 which is pivotally journalled in transverse walls 64 extending between the flanges of the beam 28. The free end of each fork shank carries a pivot pin 66 projecting into a corresponding bore in the bearing housing 46. When the bearing structure 38 moves in vertical direction it will in this manner follow a curved path but due to the small vertical movements the deviations from the straight vertical line are negligible.

As best shown in FIG. 4 the bearing housing 46 is provided with two lugs 68 to which are pivotally connected the upper ends of turnbuckles 70. The lower ends of the turnbuckles 70 are pivotally connected to arms 72 secured to torsionally rigid bars or shafts 74 extending longitudinally of the beam 28 and being rotatably journalled in brackets 76 secured to the web portion of the beam 28.

It is evident that the two shafts 74 will rotate in opposite directions when the bearing structure 38 moves vertically relatively to the beam 28.

Each sealing plate 40 consists of a central plate element 40A and two radially extending outer plate elements 40B hingedly connected to two opposite edges of the central plate element the axes of the hinges being indicated by reference numeral 58 in FIGS. 2 and 3. The shafts 74 are of substantially the same length as the central plate element 40A and to the end portions of the shafts are secured arms 78 to which are pivotally attached vertically extending pins 80 of adjustable length which pass through the beam web and at their lower ends are secured to the central plate element 40A near the corners thereof. Thus, the central plate element is suspended from the arms 78 and its weight is transferred through shafts 74 and turnbuckles to the bearing housing 46.

In cold condition of the preheater the position of the central plate element 40A relatively to the upper end surface of the rotor 10 may be properly adjusted by means of the turnbuckles 70 and the pins 80. This relative position will be maintained also when the rotor is heated because at the axial thermal expansion of the rotor and the rotor post the bearing assembly 38 moves upwardly together with the upper trunnion 12B thereby turning the shafts 74 such as to lift the pin and the central plate element fastened thereto.

From the above description it is apparent that the central plate element 40A is suspended such that it moves vertically in unison with the bearing assembly 38 without changing its spatial orientation and it is capable to withstand external forces without tilting or being deformed. Thus, the link and shaft system connecting the central plate element 40A with the bearing assembly 38 forms a stabilizing means for the central plate element.

The sealing plate 40 at the lower end surface of the rotor 10 also comprises a central plate element 40A and outer plate elements 408 as indicated by dotted lines in FIG. 6. However, in this case the central plate element 40A is not axially movable but secured to the lower beam 30 in desired position relatively to the lower end surface of the rotor by means of adjustable bolt devices 82 (only diagrammatically shown in FIG. 6).

The outer plate elements 40B of the lower sealing plate 40 are connected to the central plate element 40A by hinges 58 in the same manner as the upper ones. Near its outer end each outer plate element 408 is provided with two pins projecting through the web portion of the lower beam 30 and pivotally connected to the horisontal arms of bell cranks 84 the vertical arms of which are interconnected by a turnbuckle 86. One of the bell cranks 84 of each plate element 403 is secured to a common torsionally rigid bar or shaft 88 which extends along the beam 30 such as to compel the two bell cranks to move in unison. Rotational movements of these two bell cranks are transferred to the other two bell cranks 84 by the turnbuckles 86 so that all bell cranks 84 move in unison and prevent the outer plate elements 408 from moving in opposite directions relatively to the rotor end surface and from being skewed or tilted. For each sealing plate, a sealing strip 40C is provided to seal and cover the gap (or slit) between the respective relatively movable sealing plate elements 40A and 40B.

Each outer plate element 408 at the lower end of the rotor is connected to the outer plate element 408 at the upper end aligned therewith. This connection may be of any suitable type for instance similar to that disclosed in the above-mentioned British Pat. specification No. 1,1 18,710 but for the sake of simplicity it is in the present case shown as consisting of a link 92 (FIG. 7) pivotally connected to the plate elements. Though not illustrated this link may be made as a turnbuckle or be otherwise adjustable as to its length.

As shown in FIG. 7 pins 94 are secured to the outer ends of each outer plate element 403 at the upper rotor end and project upwardly through the web of the upper beam 28. The upper ends of the pins 94 are pivotally connected to bell cranks 96 interconnected by a turnbuckle 98. In this manner all plate elements 408 are prevented from tilting or warping.

In FIG. 7 the rotor 10 is shown fragmentarily only. Reference numeral 100 refers-to the radial partitions which are provided with sealing strips 102 cooperating with the sealing plates in known manner.

In the embodiment shown the plate elements 40A, 40B are of rectangular shape and extend diametrically across the rotor 10 so that the areas for the two fluid flows are equal.

What we claim is:

l. A rotary regenerative heat exchanger comprising: a housing: a rotor mounted in said housing, said rotor including a central rotor post and a cylindrical shell interconnected by radial partitions subdividing the rotor into a plurality of open-ended sectorial compartments for a heat exchanging mass, said housing being provided with inlet and outlet ducts for a heating fluid and a fluid to be heated and said rotor being journalled at one end in a thrust bearing means and at the otherend in a radial bearing means permitting axial movements of said other end due to thermal expansion and contraction of said rotor in the axial direction; axially movable plates between the rotor end surfaces and the end walls of the housing forming sealing means to prevent intermingling of the flows of heat exchanging fluids in the space between said surfaces and said end walls, said sealing plates including at each end of the rotor a central plate element and two radially extending outer plate elements hingedly connected to two opposite edges of the central plate element, at least one member of said radial bearing means being mounted to move axially together with said other rotor end, and the central plate element of the adjacent sealing plate being held by said bearing member; and stabilizing means carried by said housing, said stabilizing means being included in the connection between said bearing member and said central plate element and connecting the radially opposite ends of said central plate element for pre-' venting tilting of the central plate element during operation of the heat exchanger.

2. A heat exchanger as defined in claim 1, in which said stabilizing means comprise at least one rotatable, torsionally rigid bar journalled in bearings supported by the housing structure, a plurality of fastening means secured to the central plate element, a plurality of arms non-rotatably secured to and spaced along said bar, a link connecting one of said arms with said bearing member and links connecting the remaining arms with said fastening means whereby .to cause said central plate element to move axially in unison with said bearing member.

3. A heat exchanger as defined in claim 2 in which said bar is parallel with a line interconnecting the midpoints of said opposite edges of the central plate element and carries arms connected to fastening means located adjacent to said edges.

4. A heat exchanger as defined in claim 3 comprising two rotatable bars carrying arms connected to fastening means adjacent to the ends of said edges.

5. A heat exchanger as defined in claim 3 in which the central plate element is provided with a fastening means adjacent to each end of said edges, two of said fastening means being connected to arms on said bar and the two other fastening means being connected to the first-mentioned ones by means of links and bell crank mechanisms, whereby all of said fastening means move in unison.

6. A heat exchanger as defined in claim 1 in which said stabilizing means include adjustable members permitting adjustment of the position of the central plate element relative to the rotor end surface.

7. A heat exchanger as defined in claim 6 in which said stabilizing means inclusive of the adjustable members are located outside the housing.

8. A heat exchanger as defined in claim 1 in which each wall of the housing includes a substantially diametrically extending beam and said stabilizing means are carried by said beam.

9. A heat exchanger as defined in claim 1 in which the outer end of each outer sealing plate element at one rotor end is connected to the outer end of the outer sealing plate element at the other rotor end axially aligned therewith.

110. A heat exchanger as defined in claim 1 in which the outer ends of the outer sealing plate elements at at least one rotor end are interconnected by further stabilizing means preventing the plate elements from moving in different axial directions.

11. A heat exchanger as defined inclaim 10 in which further stabilizing means are provided at one rotor end, the stabilizing effect being transferred to the plate elements at the other rotor end by the connections between axially aligned plate elements. 

1. A rotary regenerative heat exchanger comprising: a housing: a rotor mounted in said housing, said rotor including a central rotor post and a cylindrical shell interconnected by radial partitions subdividing the rotor into a plurality of open-ended sectorial compartments for a heat exchanging mass, said housing being provided with inlet and outlet ducts for a heating fluid and a fluid to be heated and said rotor being journalled at one end in a thrust bearing means and at the other end in a radial bearing means permitting axial movements of said other end due to thermal expansion and contraction of said rotor in the axial direction; axially movablE plates between the rotor end surfaces and the end walls of the housing forming sealing means to prevent intermingling of the flows of heat exchanging fluids in the space between said surfaces and said end walls, said sealing plates including at each end of the rotor a central plate element and two radially extending outer plate elements hingedly connected to two opposite edges of the central plate element, at least one member of said radial bearing means being mounted to move axially together with said other rotor end, and the central plate element of the adjacent sealing plate being held by said bearing member; and stabilizing means carried by said housing, said stabilizing means being included in the connection between said bearing member and said central plate element and connecting the radially opposite ends of said central plate element for preventing tilting of the central plate element during operation of the heat exchanger.
 2. A heat exchanger as defined in claim 1, in which said stabilizing means comprise at least one rotatable, torsionally rigid bar journalled in bearings supported by the housing structure, a plurality of fastening means secured to the central plate element, a plurality of arms non-rotatably secured to and spaced along said bar, a link connecting one of said arms with said bearing member and links connecting the remaining arms with said fastening means whereby to cause said central plate element to move axially in unison with said bearing member.
 3. A heat exchanger as defined in claim 2 in which said bar is parallel with a line interconnecting the midpoints of said opposite edges of the central plate element and carries arms connected to fastening means located adjacent to said edges.
 4. A heat exchanger as defined in claim 3 comprising two rotatable bars carrying arms connected to fastening means adjacent to the ends of said edges.
 5. A heat exchanger as defined in claim 3 in which the central plate element is provided with a fastening means adjacent to each end of said edges, two of said fastening means being connected to arms on said bar and the two other fastening means being connected to the first-mentioned ones by means of links and bell crank mechanisms, whereby all of said fastening means move in unison.
 6. A heat exchanger as defined in claim 1 in which said stabilizing means include adjustable members permitting adjustment of the position of the central plate element relative to the rotor end surface.
 7. A heat exchanger as defined in claim 6 in which said stabilizing means inclusive of the adjustable members are located outside the housing.
 8. A heat exchanger as defined in claim 1 in which each wall of the housing includes a substantially diametrically extending beam and said stabilizing means are carried by said beam.
 9. A heat exchanger as defined in claim 1 in which the outer end of each outer sealing plate element at one rotor end is connected to the outer end of the outer sealing plate element at the other rotor end axially aligned therewith.
 10. A heat exchanger as defined in claim 1 in which the outer ends of the outer sealing plate elements at at least one rotor end are interconnected by further stabilizing means preventing the plate elements from moving in different axial directions.
 11. A heat exchanger as defined in claim 10 in which further stabilizing means are provided at one rotor end, the stabilizing effect being transferred to the plate elements at the other rotor end by the connections between axially aligned plate elements. 